Skin light exposure control methods

ABSTRACT

This invention relates to methods and apparatus to control the light exposure of the skin. One objective is to increase the exposure during periods of common deficient exposure such as for dark skin persons on winter days in areas far from the equator. Another objective is to decrease the exposure during periods of common overexposure such as for light skin persons during spring and summer days in bright environments. A novel feature of the invention is the use of lamps for whole body irradiation while showering or bathing during dark seasons. The whole body exposure enables the use of very low irradiance levels to provide an enhanced probability of beneficial effects and to reduce the possibility of harmful effects of the ultraviolet light. Another novel feature is the use of an adjustable ultraviolet light transmitting building window or automobile sunroof to increase the sunlight exposure on cold days when a deficiency in exposure due to closed windows is common. The increase in ultraviolet exposure enables a reduction in intake of possibly harmful excessive dietary vitamin D. Intake of foods containing antioxidants reduces the possibility of harmful effects of additional ultraviolet light. The overall objective is to provide an appropriate day-to-day balanced and moderate light exposure of the skin along with a suitable diet and exercise to increase the probability for good health.

This application is a division of application Ser. No. 08/572,110 filedDec. 14, 1995, now abandoned.

I FIELD OF INVENTION

The disclosed invention relates to methods to adjust the light exposureof the skin.

II BACKGROUND OF THE INVENTION

Diet, exercise, sleep, genetics and the environment are factorsgenerally recognized as strongly influencing health. Sunlight as adetrimental environmental factor causing skin cancer and otherconditions is often discussed. The beneficial effects of sunlight havehad much less attention.

For many individuals moderate increases in ultraviolet sunlight exposureas in outdoor work, careful sunbathing or lamp exposure can providebenefits. The benefits include: decreased blood pressure, decreasedresting heart rate, increased cardiac output, reduced blood cholesterol,increased liver glycogen stores, reduced blood sugar, increased muscularstrength and endurance, increased resistance to infections, increasedoxygen carrying capacity of the blood, increased adrenaline in tissues,increased stress tolerance, and increased hormones, Kime, 42.

The purpose of this invention is to provide methods and apparatus toincrease the exposure of the skin when the exposure might be deficientsuch as during dark winter days and decrease the exposure when theexposure might be excessive such as during bright spring and summerdays. The proper exposure of skin to solar radiation especially in achanging environment is important to promote health and reduce the riskof disease. An indoor deficiency in ultraviolet B (280 nm to 315 nm) iscommon. Excessive dietary vitamin D intake with associated problemsresults from attempts to compensate for the ultraviolet B exposuredeficiency. Methods to increase the indoor ultraviolet B (UV-B)exposure, to avoid a deficiency in exposure and possible vitamin Ddeficiency while minimizing the risk of overexposure are included.

Irregular exposure such as excessive weekend and vacation sunlightexposure for persons working indoors during the week is a commonproblem. Irregular exposure is prevalent in developed countries and is afactor in the increasing incidence of the often fatal melanoma of theskin. Another purpose of this invention is to provide apparatus andmethods to obtain a better balance in the day to day ultravioletexposure of the skin.

Not enough sunlight and vitamin D deficiency can result in poor healthand susceptibility to illness. Rickets in children, easy-to-break bonesin the elderly, a possible increased susceptibility to some types ofcancer, Ainsley, 9, and heart disease, Kime, 42, are typical conditionsassociated with insufficient UV-B sunlight exposure. The annual healthcare cost for fractures in the elderly is approximately 10 billiondollars in the U.S. alone, Avioli, 13. Scragg, 70, found coronary heartdisease mortality may be associated with vitamin D deficiency (avoidableby sufficient UV-B exposure of the skin).

Sunlight exposure is beneficial for moderating hypertension, high bloodsugar and many other conditions, Kime, 42. However, too much sunlightexposure increases the risk of skin cancer and DNA mutations. There is aneed to adjust the skin exposure to avoid both insufficient exposure andexcessive exposure. The best exposure for an individual varies with skincharacteristics. The ratio between too much and too little exposure maybe relatively small such as less than a factor of roughly three for faceand arm exposure or relatively large such as a factor of 25 for wholebody exposure.

Sunlight exposure is related to the important calcium balance. Modempopulations have a low calcium diet presumed to result in increasedosteoporosis, hypertension and colon cancer, Heaney, 38. The exposure tosunlight can increase the absorption of calcium in the intestinepartially counteracting the effects of low amounts of calcium in thediet. Also, sunlight exposure is associated with increased bonemineralization, Kime, 42. Calcium, important in the functioning ofcells, interacts strongly with vitamin D (and thus UV-B sunlightexposure), phosphorus, and magnesium. Too much calcium can result inurinary stones and interference with absorption of other essentialminerals, Williams, 84. In infancy, excess vitamin D intake may resultin hypercalcemia, Oppe, 61.

Vitamin D fortification of many foods is used in the U.S. for protectionfrom rickets and other diseases for those with insufficient vitamin Dgenerated in the skin by ultraviolet B exposure. However, the averageperson has an intake several times the recommended daily amount. Asdiscussed by Kummerow, 45, and Fraser, 27, an increased mortality andincidence of vascular disease and other conditions may be resulting fromhigh dietary intake of vitamin D. Linden, 49, found myocardialinfarction patients had high intakes of vitamin D. Knox, 43, foundincreased ischemic heart disease mortality for those with high vitamin Dintake and also for those with low calcium intake.

Fraser, 27, recommends obtaining the vitamin D from careful sun exposurerather than the diet. Along with obtaining proper exposure of the skin,the diet must be modified to avoid the excess dietary vitamin D intaketo obtain the corresponding health benefits. Increased intake of fruitsand vegetables tends to reduce intake of other foods with high vitamin Dcontent due to fortification. Although vitamin D is needed primarily inthe dark season in northern areas, the extensive fortification ispresent continuously during the year and is present in the foods forboth northern and southern areas.

Historically, problems with insufficient exposure became common in the1800's in higher latitude cities. With the start of the industrialrevolution people moved from farms to cities. The narrow streets andsmoke filled sky obscured the sunlight as shown by a photograph of atypical neighborhood, Goldsmith, 32. The incidence of rickets inchildren increased and this was later found to be due to insufficientultraviolet B solar radiation exposure. The solar radiation UV-B wasobscured both indoors and outdoors. Factory work rather than farm workgreatly reduced sun exposure.

Those still involved in farm work tend to have good health for manyconditions. The Gambia, is a West African, primarily agriculturalcountry with both men and women cultivating the crops. There issignificant outdoor exposure and a mainly vegetarian diet. This countryhas one of the lowest age standardized cancer incidences in the world.The incidence is more than five times lower than the incidence in theUnited States. In the U.S., a study in 1941 demonstrated states with ahigher percentages of farmers had a trend a for lower cancer mortalityrates. States with a higher solar radiation index had an even strongertrend for lower cancer mortality, Apperly, 12.

The rickets problem was generally solved by the addition of vitamin D tomilk and other foods. However, too much vitamin D may produce toxiceffects such as hypercalcemia, Oppe, 61. Excessive vitamin D can belethal and it is used as a rodenticide, Fraser, 27. Too much vitamin Dcan cause damage to the arteries. A typical desirable ratio ofrecommended maximum to recommended minimum dietary intake of vitamin Dfor infants is a factor of 2.5. Vitamin D generated in the skin bysunlight exposure has the advantage of only small amounts of vitamin Dbeing released. The maximum accumulated amount of sunlight generatedvitamin D in the skin is limited reducing the risk of toxic effects. Inaddition, the deleterious cholesterol in the skin and arterial plaque isreduced by sunlight exposure, Kime, 42. Cholesterol in the skin isconverted to vitamin D and other compounds by exposure to UV-Bradiation.

The narrow streets and smoke filled sky of the 1800's generally are nolonger present. However, the common economic low-melting-temperaturewindow glass blocks most of the ultraviolet B radiation. If one were tophotograph the insides of homes and businesses with an ultraviolet Bcamera, most would be dark to dim just as were the homes and streets ofthe 1800's. Bare fluorescent lamps without diffuser covers brighten theinside some. Open windows and doors in the spring and fall can brightenthe inside of homes in the UV-B just as the mood and spirit brightens insunny weather. However, now, many homes and workplaces switch fromheating to air conditioning with little or no opening of windows in thespring and fall. This leaves an indoor environment with incandescentlighting essentially continually dark in the ultraviolet B spectralregion. Hospitals with windows that do not open and fluorescent lightingwith prismatic plastic diffusers also are essentially continuously darkin the UV-B.

Those of the elderly who are inside all the time and who do not obtainvitamin D from the diet or supplements can become deficient in vitamin Dand develop weak easy-to-break bones. Even in bright countries such asKuwait, rickets occurs since children spend much of their time inside,Lubani, 51. Dark skinned persons migrating to higher latitudes canencounter vitamin D deficiency problems. Recently rickets from vitamin Ddeficiency was reported by Brunvand, 17, for Pakistani children in Oslo,Norway. One approach would be to drink more vitamin D fortified milk tocompensate for the lack of vitamin D generated by UV-B irradiation ofthe skin.

Another approach could be to increase the UV-B radiation indoors byusing UV-B transmitting windows or appropriate fluorescent lamps, anobject of this invention.

For those who spend significant time outdoors, overexposure can be aproblem in the spring and summer on bright days. During this period baretube fluorescent lamps, Maxwell, 56, open windows, or open doors canaggravate the overexposure problem during long exposure periods indoors.A method of this invention is to move ultraviolet B blocking diffusersover bare fluorescent tubes in the bright season to avoid a possibleexacerbation of the overexposure problem.

In cold climates, many persons are deficient in ultraviolet and visiblesolar radiation exposure of the skin in the winter due to blocking ofultraviolet solar radiation by window glass. Also the clothing wornoutdoors in the winter covers much of the skin greatly reducing theexposure. The short length of the day at high latitudes restricts thetime available for sunlight exposure. In addition, the low sun angle atmidday in the winter at high latitudes reduces the ambient solarirradiation due to the long path length through the atmosphere. Thesefactors make it desirable for some persons to increase the exposure ofthe skin during the cold dark season. Leach, 46, found office workers inBristol England receive less than an average of 0.7 mJ/sq. cm. per dayof biologically effective radiation, a very low value, in the darkseason from November through February, FIG. 1.

In hot climates the skin of many persons is excessively exposed to solarradiation. The long length of the summer day increases the time whensolar radiation overexposure can occur. The high sun angle at midday inthe summer increases the ambient solar irradiation due to the smallamount of scattering and absorption in the short nearly vertical pathlength through the atmosphere. These factors make it desirable for somepersons to decrease the exposure of the skin during the hot brightseason.

The solar radiation in different spectral regions, UV-B, 280 to 315nanometers, UV-A, 315 to 400 nanometers, visible light 400 to 700nanometers and infrared radiation affect various health conditions.There are several suitable window materials such as ultraviolettransmitting glass or plastic with spectral transmission characteristicsdescribed by Driscoll, 23, and Sliney, 72. The increased cost ofultraviolet transmitting materials can be partially offset by using asmall window orientated toward the sun for transmitting the solarradiation to a room frequently occupied such as a kitchen or livingroom.

The ultraviolet light rays, UV-B with a wavelength of 280 to 315nanometers, are beneficial in the production of vitamin D in the skin.However, chronic exposure of untanned skin to ultraviolet solarradiation, especially UV-B, can be associated with DNA damage and anincreased risk of skin cancer. Thus, care is needed to obtain adequateexposure in dark seasons and avoid excessive exposure in bright seasons.By reducing the bright season exposure more than the increase in thedark season exposure an increase in the risk of squamous cell skincancer can be avoided, Lytle 53. By not chronically overexposinguntanned skin an associated increase in the risk of melanoma skin cancerand other diseases can be avoided.

Vitamin D deficiency can be a problem for those confined indoors innursing or other homes with insufficient ultraviolet exposure and adeficiency in dietary vitamin D. In some areas, especially far from theequator, there may not be sufficient sunlight for vitamin D generationin winter months. In addition to latitude, weather affects sunlightavailability.

Dietary or tablet supplements are commonly used to avoid vitamin Ddeficiency. However, there may be problems associated with the use ofdietary and tablet supplement vitamin D rather than solar radiationgenerated vitamin D. Large amounts of dietary or tablet supplementvitamin D can be ingested, however, vitamin D generated in the skintends to self limit. Accumulated cholecalciferol blocks furthersynthesis of vitamin D in the skin, Heaney, 38. Fraser, 27, states:"Evidence from domestic animals suggests that persistent feeding ofdietary vitamin D may be associated with the development of chronicvascular disease. For this reason alone it is prudent to advise thatvitamin D should be obtained from the environment by careful exposure ofthe skin to solar ultraviolet light rather than from the artificialsource of dietary supplements."

Latitudinal variations in incidence and mortality

In addition to rickets and other disorders being associated with vitaminD deficiency, Garland, 29, postulates the increased breast cancer formore northerly, lower-solar-radiation areas in the United States mayresult from reduced solar radiation generated vitamin D. Colon canceralso is possibly associated with vitamin D deficiency by Garland, 30.Ovarian cancer also tends to have lower mortality rates for U.S. womenliving in areas with more sunlight, Lefkowitz and Garland, 47. Forprostate cancer, Studzinski, 77, discusses the studies indicating anincreased mortality rate with reduced ultraviolet exposure, increasedrisk associated with higher serum levels of vitamin D binding proteinand decreased risk associated with higher levels of serum 1,25 vitaminD3.

Multiple Sclerosis also has lower incidences in more southerly areas,Mason, 55. Many MS patients were found to be vitamin D deficient byNieves, 59. Since heat intolerance is associated with MS and many arehomebound without sunlight exposure, the deficiency was associated withbeing a result of the disease rather than a possible cause. However thelatitudinal variation being similar to breast and colon cancer indicatesvitamin D deficiency, solar radiation or climate induced processes mightbe considered as a partial cause, risk factor or aggravating factor forincreased incidences of the disease. Waksman, 81, recommends influencessuch as climate, general levels of infection and neuroendocrineprocesses be investigated. Light induced neuroendocrine effects may berelevant.

Equatorial regions tend to have low cancer incidences. The hot desertregions near 30 degrees latitude and the colder darker areas beyond 30degrees latitude tend to have higher incidences for many types ofcancer. For the equatorial regions the climate tends to be more uniformthroughout the year with the length of days and nights balanced. Thewarm equatorial temperatures enable more skin to be exposed and theexposure is relatively uniform throughout the year. Also the diet tendsto have more fruit and vegetables with low fat intake. The yearly solarradiation tends to be higher in the desert regions rather than at theequator. The fat intake tends to be higher for the developed countriesat higher latitudes.

The many high population density areas near the equator tend to resultin migration out of the area. The low rate of inward migration leaves apopulation with skin type well adapted for the local solar radiationenvironment over a very large number of generations. In lower populationdensity areas at higher latitudes many dark skin persons are living inareas with low solar radiation exposure and many with light skin areliving in hot bright climates. Increased migration has resulted in manyliving in stressful environments. The methods of this invention aredirected toward increasing the exposure for those with skin betteradapted for brighter environments and decreasing the exposure for thosewith skin better adapted for a darker environment.

For skin and some other cancers the average incidence decreases withincreasing latitude above 30 degrees north. These registries areprimarily light skin registries. The higher incidences are in many casesfor many persons with light skin living in brighter areas than theirancestors in northern Europe. For squamous cell and basal cell skincancer the decrease is usually attributed to the lower total solarradiation dose at the higher latitudes. For melanoma of the skin thehigh incidences are often attributed to chronic exposure of untannedskin. An example is an indoor worker spending a lot of time in thesunlight on weekends and vacations resulting in many sunburns.

Seasonal mortality variations

If insufficient sunlight exposure and associated low vitamin D in thewinter is associated with increased risk of diseases such as breast andcolon cancer, an increase in mortality in the winter is a possibleconsequence. For those diseases with increased mortality at higherlatitudes with colder darker environments in the winter it might beexpected to find an increased mortality in the winter months.

Since respiratory diseases are much more common in the low-temperaturelow-humidity winter season, increased incidences of other diseases areoften considered to be a result of decreased resistance due to therespiratory conditions rather than reduced sunlight or a combination.The winter increase in respiratory diseases is large as shown in FIG. 2.

The mortality values for many other disease categories also areincreased in the winter season, but not as much as for respiratorydiseases, as illustrated by FIG. 2. The mortality for breast and coloncancer are slightly increased in the winter as shown in FIG. 3.

The seasonal variation of total mortality in Alaska is significantlydifferent than the other states as illustrated by a comparison of FIGS.2 and 4. In two years shown, 1989 and 1990 there is a narrow winter peakand a wide summer peak as shown in FIG. 4. In earlier years such as 1970the summer peak is present in the vital statistics mortality tables forAlaska. A possible cause for part of the summer mortality peak, otherthan ultraviolet exposure, is the reduced melatonin associated with theshort summer nights in Alaska. Decreased melatonin resulting from lightat night, Blask, 16, has been postulated to be associated with increaseddisease incidence such as increased breast cancer.

The detrimental effects of short summer nights may be reduced by usingroom darkening curtains and low temperatures in the bedroom to make itpossible to obtain adequate sleep in the summer, not only in Alaska, butin other states as well. Additional factors may be of importance inmaintaining a sufficient melatonin concentration and duration. Increaseddisease incidence from living near electrical power lines or equipmentwith associated high electric and magnetic fields is believed topossibly be due to suppression of the nocturnal melatonin concentrationas measured in animals, Kato, 41.

Mortality and incidence differences for males and females

In many western countries many females have increased sunlight exposuredue to not working in an office or factory. Also, clothing styles inmany countries tend to have more skin exposed for females than for malessuch as exposed lower legs for females. For many disease categories suchas malignancies, females have lower mortality rates as would be expectedif the average exposure is less than the optimum for best health. Insome countries, such as Peru and Israel, males have lower malignancyincidence rates than females, WHO, 86, indicating the average exposuremay be greater than optimum for females and possibly also for males.

In countries with a clothing style for females with most of the skincovered, the malignancy incidence rates for females is greater than formales such as in some registries in India, Parkin, 62. This indicates apossible underexposure for females. Techniques for obtaining additionalprivate exposure (in conformance with religious beliefs) may offerhealth advantages for females.

Circulatory disease mortality, countries with and without extensivevitamin D fortification

In the U.S. many foods are fortified with vitamin D. In the U.K.,France, Belgium, and the Netherlands fortification is used mostly forinfants with small amounts for adults. The Netherlands specificallyprohibit vitamin D fortification for items other than margarine andinfant formulas according to the Tracor-Jitco report, reference FDA, 24.As shown by the mortality trends in FIG. 5, the Netherlands has a lowall causes death rate and low circulatory system death rate. SinceFraser has associated dietary vitamin D with vascular disease, thecirculatory disease mortality would be expected to be higher in the U.S.than the other countries not having vitamin D fortification for adulthigh intake dietary items such as bread, breakfast cereal, and milk.

Since there are many differences between the U.S. and the othercountries other than vitamin D intake, the mortality difference may bedue to other factors. For example, the lower circulatory diseasemortality rate in France may be partially due to the regular consumptionof moderate amounts of wine. However, since data for animals, Kummerow45, demonstrates the adverse effects of excessive vitamin D, it isreasonable to consider vitamin D as a possible cause for part of themortality differences.

FIG. 5 shows the generally higher age standardized incidence ofcirculatory disease in the U.S. compared with the countries withoutextensive adult dietary vitamin D fortification. Only for the U.K. forthe last three periods is the circulatory death rate higher than theU.S. rate. Factors other than the vitamin D fortification may beresponsible for the differences but the data indicate a significantfraction of the circulatory disease mortality possibly may be associatedwith vitamin D fortification.

In the U.K., the dietary intake of vitamin D was estimated to be 116 to133 IU/day according to the FDA report, 25, by the Fed of Am Societiesfor Experimental Biology. In 1967 Dale and Lowenberg, 20, estimated theintake for 150 U.S. subjects to be 547 IU/day. In his 1979 publication,Kummerow, 45, estimated the per capita U.S. intake to be about six timesthe RDA of 400 IU or about 2435 IU/day a very high value. However thisvalue is based on the 10,000 lbs. of vitamin produced in the U.S. Ofthis 10,000 lbs. only 4000 lbs. was sold in 1969 (Tracor-Jitco report,FDA, 24) so the per capita intake is about 1000 IU/day or somewhat lessconsidering losses in the amount sold prior to intake.

Exposure for Vitamin D generation

The amount of skin exposure needed for vitamin D generation is notgreat. According to Mary Ellen Siegel, 72, the exposure time requiredfor solar radiation induced vitamin D generation outdoors is only about15 minutes of exposure of any area every two or three days. About 18IU/sq. cm. per 3 hour period is generated in skin exposed to sunlightaccording to Loomis, 50. Thus, for 200 sq. cm. of skin exposed for 0.3hours, 360 IU of vitamin D, or less due to limiting, would be expected.An ultraviolet transmitting window in a dwelling can provide sufficientexposure at a lower irradiance indoors for a longer exposure period. Ina review article Anderson, 11, stated:

"The amount of skin biosynthesis per day is affected by many factors,such as latitude, sun (UV) exposure, dress, season of year, and skinmelanin pigmentation. Webb, 82, estimated that only 15 to 20 minutes ofexposure of arms and face at midday (c. 2 pm) will yield sufficient skinproduction of vitamin D sufficient to meet daily needs of adults livingin Boston, Mass., U.S.A. i.e., 5 micrograms (or 200 IU). In the elderly,however, almost twice as much time is required to yield the same amountof vitamin D production by the skin." These times are only for favorableseasons since Webb, 82, stated in his title: "Exposure to wintersunlight in Boston and Edmonton will not produce vitamin D3 synthesis inhuman skin."

Exposures measured by Leach, 46, for office workers in Bristol Englanddemonstrate a long period in winter with very low average exposures asshown in FIG. 1. In the winter season dietary vitamin D intake or lampexposure can be used to obtain sufficient vitamin D. Excess dietaryvitamin D intake is a potential problem. In the summer season, care canbe used to avoid excess exposure. For office workers, a particularproblem is the weekend and vacation exposure of untanned skin which canincrease the risk of melanoma of the skin. The exposures for vitamin Dgeneration are low for a person with typical light skin. For those withdark skin higher exposures are necessary.

Whole body exposure has the advantage of a much lower exposure per unitarea of skin. This greatly reduces the risk of skin cancer. Also, thecholesterol in the skin and arterial plaque is reduced over a muchlarger area than the commonly exposed areas such as head and arms.Ainsley, 9, recommends periodic sunbathing for the exposure. This ispractical in locations with favorable climate such as parts ofCalifornia. However in most areas the primary exposure deficiency occursin the season too cold for outdoor sunbathing. Thus lamps or ultravioletB transmitting windows are needed. Proper levels of exposure enablereduction or elimination of excessive dietary vitamin D currently beingconsumed by many individuals with potential adverse health consequences.

Since one MED (Minimal Erythema Dose) whole body exposure producesapproximately 10,000 IU, Goldsmith, 32, p. 939 and the adult recommendedamount is 200 IU, one MED is a factor of 50 more than needed. For anadult a whole body exposure of 1/50 MED should be sufficient in thewinter in latitudes where an insignificant amount of solar radiationgenerated vitamin D is produced and a significant amount of vitamin D isnot obtained from the diet or supplements.

For the elderly, lactating women and children, the recommended amount is400 IU so the maximum whole-body exposure needed for vitamin Dgeneration for this group is 1/25 MED. An exposure less than the maximumis needed for those with significant vitamin D from casual solarexposure, the diet and supplements.

Dietary vitamin D intake

As discussed previously, the estimated per capita dietary vitamin Dintake in the U.S. was 2435 IU per day, Kummerow, 45. Since Kummerow'sestimate was based on the amount of vitamin D produced and only 40% ofthe amount produced was sold, FDA, 24, the corrected intake was about1000 IU/day or less depending on the fraction of the amount sold thatwas consumed. Dale, 20, estimated the average daily intake to be 477 IUfor older adolescents. The recommended daily intake for adults 25 yearsof age and older, other than pregnant or lactating women, is a lowervalue of 200 IU, Williams, 84. The average U.S. vitamin D intake ishigher than the recommended intake for adults by a factor of 2.7 usingDale's estimate or a factor of 5 using the 1000 IU/day estimate.

According to Kummerow, 45, the vitamin D is added to: " . . . babyfoods, imitation dairy products, beverages, sweet sauces, preparedbreakfast cereals, margarine, macaroni, noodles, farina, and flour. Moststore bread has 250-750 IU/lb. added." The toxic level of 2000-3000 IUper day, Reed, 67, is not extremely high compared to the per capitaintake. For infants Sterns, 76, concluded the upper safe level to bebetween 800 and 1,500 IU per day since intakes in this range result indecreased growth. In addition to the other sources, vitamin D is addedto animal feeds and then indirectly consumed in meat and eggs. Vitamin Doccurs naturally in only a few food sources such as yeast and fish liveroils, Williams, 84. In countries such as the Netherlands where vitamin Dis added only to infant formula and margarine, the age standardizedcirculatory disease death rate is much less than in the United States.Belgium and France also have low average dietary vitamin D intakes. Inthese countries the vitamin D is added to only a few food items.

Table 1 includes an estimate of vitamin D intake using food content datafrom several sources including Kummerow's values.

                  TABLE 1    ______________________________________    Vitamin D intake estimate                                         Estimated                                         Intake**                         Typical  Calculated                                         Dale and               Consumption                         content* intake*                                         Lowenberg    Food Item  lbs./year IU/lbs.  IU/day IU/day    ______________________________________    Wheat      111       500      152    Other cereals               22        784      46      0-35    Total rice  7         7        0    Total sugar and               119    sweets    Total potatoes and               100    starchy foods    Total pulses, nuts,               15    seeds    Total vegetables               206        6        3    Total fruit               156    Cocoa       3        1300     11      8-38    Beef       115        90      28    Veal        3         90       1    Pig meat (pork and               65        410      73    bacon)    Mutton, lamb and                3         90       1    goat meat    Poultry meat               50        363      50    Total eggs 38        245      25    Total milk products               369       200      202    325-387    Cheese (hard)               13         16       1    Cottage cheese                5    Total fish and               16        2700     118    crustaceans    Total oils and fats               54                  0    (fat content)    Margarine  11        1900     58     26-47    (fat content)    Butter      5        2700     36    (product weight)                         Total:   806    477    ______________________________________     References: Dale and Lowenberg: J. of Pediatrics, 70:952-955;1967     OEDC (Organiz. Econ. Coop. & Develop.), Food Consumption Statistics,     Paris, 1978     Kummerow: Am. J. Clin. Nutr, 32:58-83;1979     Kummerow: Am. J. Clin. Nutr, 29:579-584;1976     Wilson, Principles of Nutrition, Wiley, 1975, p486     Pennington, Food Values of Portions Commonly Used, 15th Ed. 1989.     Mutton, lamb and goat estimated using beef content value     *For choice of food items with high vitamin D content.     **Catagories not listed: Diet foods 0-20 IU/day; Natural foods 20-66     IU/day.

A vitamin D intake from bread, meats other than lunch meat, poultry, andfish are not included in the table by Pennington, 64. If a person eatsbread fortified with vitamin D the intake can be high. If a person eatsa high percentage of lunch meat the vitamin D intake can be high asindicated by the values in Pennington's table. If other meats have ahigh content as measured by Kummerow, the vitamin D intake can be high.If vitamin D rich fish is consumed the intake can be high. If breakfastcereal fortified with vitamin D is used the intake can be high. Iffortified margarine and butter are used the intake can be high. Thecombination of these items results in an estimated intake of over 800 IUper day as listed in table 1. This large value is not greatly less thanthe 1000 IU per day value derived from the amount of vitamin D that wassold in one year.

Many persons can have an intake of vitamin D higher than the average dueto variations in dietary habits and the use of vitamin pills. Intake oftoxic levels of vitamin D may be having serious consequences for largenumbers of persons. Excess vitamin D from the diet may result inprecipitation of calcium salts in the kidneys and arteries resulting inirreversible kidney damage and calcification of major arteries.

Bone mineralization

Sunlight exposure to obtain vitamin D rather than obtaining the vitaminD from the diet has the advantage the exposure may result in addedcalcium to increase bone mineral density resulting in stronger bones.Also, a reserve supply of calcium in the bones is obtained for useduring any periods when there may be a net loss of calcium.

Licht, 48, provides an ancient history reference to long term sunlightexposure of shaved heads resulting in increased skull mineralization incomparison with those with less long-term sunlight exposure due toheadwear and hair covering. The increased skull mineralization decreasesthe transmitted light to the outer layers of the brain and acts in amanner similar to the tanning of the skin to protect underlying tissues.Increased bone mineralization may also serve to protect the bone marrowand blood forming processes. A rapidly changing environment such as avacation to a sunny beach area does not allow time for protectivemechanisms such as bone mineralization in addition to tanning tooperate. This raises the possibility of light overexposure affectingdisorders other than just the skin.

The calcium for increased mineralization is supplied by increasedultraviolet light resulting in higher dietary calcium absorption in theintestine. Kime, 42, described an experiment comparing fluorescent lamplighting resulting in increased calcium absorption while incandescentlighting resulted in decreased calcium absorption for two groups ofveterans living indoors in a soldiers home in Chelsea, Mass.

Vitamin D in animal rations

The control of the inside optical radiation environment for farm animalsis desirable to enable the use of less vitamin D in animal rations.Reduced vitamin D in animal rations decreases the vitamin D intake ofhumans consuming meat. For those persons with excess vitamin D intake areduction in vitamin D consumption may result in improved health andextended life span.

By using adjustable ultraviolet solar radiation from skylights in farmbuildings it may be possible to reduce the amount of vitamin D in animalfeed without reducing the food productivity. For a skylight, anadditional outer reflecting section may be necessary to preventexcessive heating from the greenhouse effect for hot days. The overallreduction in the fortification of foods to reduce the per capitaconsumption to a value near the recommended daily allowance may havepotential to significantly improve health. Obtaining more vitamin D fromultraviolet skin exposure and less from dietary intake appears to bedesirable as long as great care is taken in avoiding skin overexposureas discussed by Fraser, 27.

Antioxidants

When using increased skin exposure in place of dietary vitamin D,antioxidants in the diet have increased important. According toShigenaga and Ames, 71, the oxidant singlet oxygen is generated fromoxygen by the absorption of energy from a dye activated by light. Theyalso point out: "It has been estimated that approximately 30% of allcancers are related to the diet and that the main culprit is a dietaryimbalance of too few fruits and vegetables and too much fat."

The antioxidants Vitamins C, E and beta carotene provide resistance tosome of the adverse effects of exposure. Thus, fresh fruit andvegetables containing antioxidants are important to include in the dietto reduce DNA damage. The use of as grown food in place of processedfoods such as some breakfast foods and prepared frozen foods has otherhealth advantages such as reduced trans fatty acid intake. Since DNAabsorption and vitamin D formation in the skin have similar actionspectra, care in skin exposure along with the diet is necessary toreduce the risk of excessive unrepaired DNA damage.

Beneficial effects of sunlight other than vitamin D formation

Solar radiation exposure has many other beneficial health effectsbesides the beneficial influences on vitamin D generation. The MarylandHeart Association found sunbathers suffer from hypertension only half asmuch as the general population, Kime, 42.

The exposure of the skin to an appropriate amount of blue or green lightis beneficial to detoxify and stimulate the elimination of a naturalmetabolite, bilirubin. In the absence of light, bilirubin has to beconjugated with glucuronic acid or other sugars to be excretedeffectively, McDonagh, 57. An example of the beneficial use of increasedskin illumination using blue or green light is the phototherapy used fortreating neonatal jaundice.

Seasonal affective disorder, SAD, is another condition treated usingvisible light. In dark seasons, bright artificial lights are used duringreading or in the viewing direction to moderate or eliminate depression.

The nocturnal melatonin concentration depends on the circadian rhythmdetermined by the light variation between night and day. As discussed byBlask, 16, a high melatonin concentration may be important for lowincidence for several types of cancer. Blocking the early morningsunlight in the summer by shades at windows may provid a health benefitby extending the nocturnal period of high melatonin concentration.Avoiding late night activities such as television viewing also mayextend the period of high melatonin concentration.

Further, certain skin diseases, such as psoriasis and vitiligo amongothers may be partially alleviated by exposure to sun light orultraviolet radiation, UV-A, with wavelengths between 315 and 400nanometers, Bortnick, 1. Consequently a window of light transmittingmaterial or lamp allowing the irradiation of skin may aid in thetreatment and prevention of these and other diseases.

Possible detrimental effects of sun or lamp exposure

In addition to the beneficial effects of solar radiation exposure thereare many possible detrimental effects of excessive skin exposure.

Nonmelanoma skin cancer from excessive accumulated solar radiationexposure has a very high incidence. In 1977-78 the number of new casesper year was over 2 per 1000 persons, WHO, 85, page 139. Nonmelanomaskin cancer does not have a high fatality rate similar to the lowerincidence melanoma of the skin, however the incidence of melanoma of theskin is increasing in many areas such as Australia.

Simone Harrison, 36, found rapid development of melanocytic nevi duringchildhood in Australia. A large number of melanocytic nevi is a riskfactor for melanoma skin cancer. Very high counts in the study inAustralia were associated with estimated sun exposures of four or morehours per day. For light skinned persons in bright environments such asAustralia, ultraviolet transmitting windows may not provide an advantagefor much of the year. If an advantage is provided it may be for only afew brief periods.

Mangus, 54, postulated the increasing incidence of melanoma of the skinin the Nordic countries is associated with changing clothing styles andvacations. The changing clothing styles result in increased skinexposure on bright spring and summer days. Vacations to more southerlylatitudes result in exposure of untanned skin to a bright solarradiation environment. A more uniform exposure to ultraviolet radiationthroughout the year using UV transmitting windows may provide manyhealth benefits without the detrimental effects associated with briefvacations to bright areas or utilization of tanning booths. Infants andchildren in strollers without sunshades may be subjected to overexposureespecially if exposed for long periods in midday during bright summerdays. Irregular exposure, being indoors much of the time, followed by aday with lots of outdoor exposure is very undesirable and a risk factorfor melanoma of the skin. In the darker times of the year there is theopposite problem of obtaining sufficient exposure with the manyassociated beneficial effects.

Conditions other than skin cancer may have an increased risk resultingfrom solar radiation overexposure in bright seasons. Immune systemsuppression by ultraviolet radiation, Goettsch, 31, may result inincreased incidences of many types of immune system related conditions.Also, ultraviolet radiation can activate the human immunodeficiencyvirus-1 promoter, Valerie, 78, or the virus, Stanley, 75. Effects ofmultiple ultraviolet exposures on transcription induction from the longterminal repeat of the human immunodeficiency virus were measured bySchreck, 68.

As discussed by Nowak, 60, the HIV virus may overcome the immume systemby many mutations developing a resistant strain of the virus. Theavoidance of excess mutation inducing ultraviolet exposure by those whoare HIV positive may extend the latent period. Cebula, 19, describestechniques to compare lamps for selection of lamps with minimummutagenic effects. However, ultraviolet exposure is associated withstrengthening of some of the properties of the immune system. As listedby Hawk, 37, excess ultraviolet exposure can exacerbate viral infection.Until it is determined whether or not the latency period is dependent onultraviolet exposure, it is unknown if the lamp exposure will bedetrimental, beneficial or not have an effect for those who are HIVpositive. Ultraviolet-B phototherapy has not demonstrated adverse shortterm effects for 28 HIV positive patients, Fotiades, 26. If sunlightinduces the progression of AIDS, Vincek, 80, hypothesizes TNF alpha(tumor necrosis factor-alpha) and cis-UCA (urocanic acid) released byintense sun exposure can accelerate the onset and progression of AIDS inHIV-infected individuals.

Relevant patents

The many advantages of obtaining sufficient exposure in the dark seasonsand avoiding excessive exposure in the bright seasons demonstrate theneed for methods and apparatus to assist in obtaining proper exposure.There are existing patents of use in conjunction with the presentinvention to achieve improved exposure of the skin.

The patent by Bortnik, U.S. Pat. No. 4,546,493, refers to tan throughgarments. The types of materials used can be irritating to the skin. Byusing windows in conventional garment material the possibly irritatingmaterial can be offset from contact with the skin to reduce thepossibility of irritation. This material can provide needed additionalskin exposure in dark seasons.

The patent by Calverley, U.S. Pat. No. 5,206,229, describes vitamin Danalogs for pharmaceutical use. The disclosed invention refers tomethods to obtain benefits by the use of ultraviolet induced vitamin D.

The patent by Fiorenza, U.S. Pat. No. 4,656,778, describes a three trackstorm window. By use of a ultraviolet transmitting window in one (theouter) of the three tracks and ultraviolet blocking windows in the othertwo tracks, a window with adjustable ultraviolet transmission can beobtained.

The patent by Ryan, U.S. Pat. No. 5,196,705, describes an exposure meterthat can be used to adjust the ultraviolet transmission for anappropriate exposure either higher or lower.

The patent by Rattray, U.S. Pat. No. 4,843,279, describes a fluorescentlamp that can be used to obtain high levels of adjustable ultravioletradiation exposure in the disclosed fixture with adjustable ultraviolettransmission.

The patent by Pepall, U.S. Pat. No. D282,581, describes a sunlamp thatcan be used with the disclosed adjustable ultraviolet transmissiondevices to obtain an appropriate ultraviolet exposure.

The patent by Dalebout, U.S. Pat. No. 5,000,444 describes a dual actionexercise cycle with air resistant blade members in back. This exercisecycle is particularly well suited for the addition of irradiation lampsin back. The air blades provide air circulation for cooling of theseated individual. The air cooling helps to compensate for theadditional heat from the lamps.

The patent by Young, U.S. Pat. No. D310,878 describes a tanning stationfor use with exercise devices. The irradiation devices of this inventiontypically use lower irradiances with doses less than the level fortanning. The irradiation devices of this invention are selected forvitamin D formation and potential reduction of risk of particular typesof cancer, heart disease and other conditions. Tanning lamps commonlyuse predominantly ultraviolet A irradiation. For vitamin D generation inthe skin ultraviolet B radiation is normally utilized.

III OBJECTS OF THE INVENTION

The primary object of the invention is to provide a method and apparatusto adjust the exposure of the skin to optical radiation.

Another object is to obtain a skin exposure favorable to good health andavoidance of disease.

A further object is to provide a skin exposure for formation of anappropriate amount of vitamin D in the skin so excessive vitamin D inthe diet can be reduced or eliminated.

An additional object of the invention is to maintain the warmth andcomfort in cold environments provided by similar devices withoutadjustable features.

Still another object of the invention is to provide a device that isdurable, easy to adjust and has a pleasing appearance.

Yet a further object of the invention is to provide an adjustable devicethat may be used in the treatment of skin diseases for which exposure tooptical radiation is beneficial.

Another object is to provide a method and apparatus to adjust theinternal ultraviolet, visible and infrared radiation environment tolevels suitable for an individual with particular skin characteristics.

An additional object is to provide a method and apparatus to adjust theinside optical radiation environment for an improved balance through thechanging seasons.

Another object is to provide a method and apparatus to keep the skinirradiance low to keep the risk of detrimental effects, including skincancer, low.

Another object is to provide a method and apparatus to have whole bodyradiation to reduce the cholesterol in the skin, artery plaque and othertissue.

Another object is to provide a method and apparatus to have whole bodyradiation to generate vitamin D at the lowest possible irradiance (tokeep the detrimental effect risk low).

Another object is to provide a method and apparatus to have whole bodyradiation over a long time period to allow the body blood pool tocirculate through the irradiated skin.

IV SUMMARY OF THE INVENTION

Some or all of these objectives can be achieved by using an ultraviolettransmitting window or lamp for simulated sunbathing in dark seasons forpersons needing additional exposure. This makes it possible to reduce oreliminate the need for dietary vitamin D with potential associatedproblems. Care in bright season exposure enables the yearly exposure tobe reduced even with increases in dark season exposure. The intake offive servings of fruits and vegetables, low in vitamin D content, eachday helps to reduce the intake of the many other foods with high vitaminD content for persons with excess vitamin D intake.

The use of a lamp in the bathroom enables whole body irradiation duringbathing without requiring additional time for a person with a busyschedule;

The bathroom is the room often kept warm enough for an unclothed personin cold areas far from the equator;

The use of an adjustable lamp, such as by an adjustable window in frontof the lamp, or less time, allows a reduced exposure during spring andfall seasons when sunlight exposure and diet provide part of therecommended daily allowance of vitamin D.

Exercise clubs, gymnasiums and indoor swimming pools are areas whereclothing exposing more skin than usual is worn. These areas offeropportunity for closer to whole body irradiation during the darkseasons. The benefits of exercise are obtained and the exposure isachieved at the same time without requiring additional time for busypersons.

Exposure values needed in dark seasons for some persons

If a lamp is used to provide additional vitamin D, then the amountneeded is determined from the difference between the recommended amountand the amount from solar radiation generation, the diet andsupplements. The MED varies between individuals being low for light skinpersons and high for dark skin persons. For example, Westerhof, 82,lists some typical values for 17 individuals ranging from 30 mJ/sq. cm.to 381 mJ/sq. cm., using a 20 nm wide (halfwidth) filter centered at 298nm for the UV-B measurements and mercury arc lamp simulating the solarspectrum. Berger, 17, describes other lamps for simulating the solarspectrum for MED measurements. These lamps also can be used forstimulating vitamin D generation in the skin.

Since outdoor workers have lower mortality rates than indoor workers,exercise and an increased exposure for indoor workers may improvehealth. Outdoor workers obtain an exposure of about 10% of the ambientenvironment while indoor workers obtain about 3% for a weekly average,WHO, 85. The exposure of office workers could be increased by a factorof about 3.3, along with increased exercise, and an overall improvementin health may be achieved.

Overall, there is a need for an appropriate level of skin irradiationfor various wavelengths to obtain beneficial effects for health. Adeficiency in exposure may occur especially for dark skin persons incold dark seasons. There is a need to have moderation in the exposureand avoid overexposure especially in hot bright seasons for light skinpersons. There is a need for balance in the exposure through theseasons, particularly in the latitudes with large fluctuations in theenvironment.

As there is a need for recommended daily allowances for different dietitems without excesses, there is a need for an appropriate daily skinirradiation for different wavelengths without excessive overexposure.Preferably the ranges are 0.02 MED for whole body exposure to 0.2 MEDfor 10% of whole body exposure for vitamin D generation. Multipleexposures over one MED greatly increase the risk of skin cancer. Theminimum dose requirement established by the Health Council of theNetherlands, 1986, World Health Organization, 85, is 55 MED per year orabout 0.15 MED per day. This value is slightly less than the above valueof 0.2 MED per day value for a person with 10% whole body exposure.

Relative to the amount of energy for longer wavelengths favorable foruse with the UV-B exposure, one study was conducted for light exposureeffects on carbohydrate metabolism. Pincussen, 65, found the relativeenergy in the ultraviolet and visible regions in sunlight producesfavorable maximum ratios of glucose to lactic acid in the blood andmaximum ratios of glycogen to lactic acid in the liver and muscle inanimal carbohydrate metabolism experiments. By use of the sunlightspectrum the exposure energy for longer wavelengths can be estimated.These exposure values can then be modified as necessary for specialpurposes and individual requirements.

Using the relative energy in sunlight for different wavelengths on cleardays with the sun near the zenith, the doses for the UV-A, and thevisible and IR irradiation can be estimated. For sunlight, the UV-A doseis roughly 30 times the UV-B dose. The visible and IR dose is roughly 20times the UV-A dose.

Typical outdoor summer exposure rates measured by Diffey, 22, for lightskin persons range from less than 0.01 MED per hour walking in the shadeto 0.24 MED/hour while walking on a beach on a cloudy day to as high asa maximum value of 2.3 MED/hour while driving a car with the windowsopen.

An exposure of 1 MED in a day indicates the normal capability of theskin to repair the damage is exceeded representing an overexposure. Forpersons with conditions such as xeroderma pigmentosum with defective DNArepair capability, or sarcoidosis, Bell, 15, exposure requires specialprecautions.

One technique to avoid excess exposure in the summer is to use care instaying out of the direct sunlight when the shadow is shorter than theheight of a person. This provides a sun protection factor of about 2.7or greater due to the long path length through the atmosphere comparedwith the time when the sun is near the zenith and when shadows areshort, Holloway, 39. One factor to help keep the risk of squamous cellcarcinoma skin cancer low is to maintain a low total yearly exposure(total MED's), Lytle, 53.

One factor to help keep the risk of melanoma skin cancer low is to avoidchronic exposure of untanned skin. An example is avoiding getting manysunburns or high doses on vacations or weekends while being inside muchof the time during the week.

Use of lamps for exposure in dark seasons

Since MED's range from about 30 to 381 mJ/sq. cm., an exposure of 1/50MED for whole body exposure ranges from about 0.6 mJ/sq. cm. to 6.3mJ/sq. cm. for light skin persons to blacks. For a 1000 second (17minute) exposure the corresponding range in irradiance is: 0.6microwatts/sq. cm. to 6.3 microwatts/ sq. cm. According to Maxwell, 56,fluorescent lamps produce up to about 0.14 microwatts/sq. cm. (0.0070microwatts/sq. cm. nm*20 nm) at a location where the illuminance is 500lux. Thus a single bare tube fluorescent lamp (with a high UV output)may be suitable for generating roughly 25% of the recommended dailyvitamin D for a light skinned person during a 17 minute period of wholebody exposure. To provide a higher percentage of the recommended dailyvitamin D, a filter for the visible light that transmits the ultravioletB radiation can be used to enable additions lamps to be used withoutexcessive brightness.

Some quartz halogen lamps produce 0.2 microwatts/sq. cm. of effectiveultraviolet radiation and greater at a distance of 30 cm., WHO, 85, page227. Thus, these lamps in addition to fluorescent lamps are suitable forstimulation of vitamin D formation in the skin.

For a precise evaluation of the percentage of the recommended vitamin Dprovided by a lamp the spectral variation of the MED, Parrish, 63, andthe lamp spectrum can be used. Lamp spectra and the MED both varygreatly with wavelength in the UV-B spectral region.

The times of the year when there is a deficiency in exposure has notbeen measured extensively. Leach, 46, measured the exposure throughoutthe year for office workers in Bristol, England, FIG. 1. He foundaverage daily values of less than 1 millijoule/sq. cm. in the winter andgreater than 8 millijoules/sq. cm. in the summer. For a light skinnedperson with an MED of 30 millijoules/sq. cm. a 0.2 MED exposure for 10%whole body exposure is 6 millijoules/sq. cm. In Bristol, for officeworkers, the exposure was over 6 millijoules/sq. cm. only for weeksapproximately 21 through 34. Since vitamin D tends to accumulate overmany days the vitamin D may be sufficient over more than the 13 weeks inthe hot season. However, the need for additional exposure in the largenumber of remaining weeks is evident if excess dietary vitamin D intakeis to be reduced.

For locations at lower latitudes a longer period with daily exposureover 6 mJ/sq. cm. is usually expected. For these areas the number ofweeks with low exposure is correspondingly reduced For very bright areasthe ambient solar radiation exposure may be sufficient for the entireyear. However, even with sufficient sunlight, if there are notsufficient outdoor periods while wearing suitable clothing the skinexposure may still be deficient.

The sufficiency of the combined effects of exposure and dietary vitaminD intake is indicated by the circulating vitamin D in the blood. Thelevels of a primary vitamin D component in the blood, 25-OHD, weremeasured throughout the year in Denmark by Lund, 52. The summer levelsare about 13 ng/ml greater than the winter levels. In the U.S. thesummer levels are about 12 ng/ml greater than the winter levels forindoor workers, Neer, 58. The dietary vitamin D intake in the U.S. isvery high and the average annual 25-OHD levels range from about 40 ng/mlfor persons in the north, Seattle and Boston, to over 80 mg/ml forpersons in the far south, Palm Beach, Neer. In France, were vitamin D isadded to only a few food items, the average 25-OHD levels were found tobe 10 ng/ml to 20 ng/ml by Bayard, 14.

Levels of 25-OHD of 2 to 7 ng/ml are associated with rickets as shown bythe observations of Bayard. In a case control study in Auckland, NewZealand Scragg, 70, found the risk of myocardial infarction for a groupwith plasma 25-OHD levels above the median level of 12.3 ng/ml was only43% of that of the control group. Garland, 30, recommends a 25-OHD levelof 27 to 41 ng/ml to maintain a low risk of colon cancer.

The current average levels of 40 ng/ml to over 80 ng/ml in the U.S. witha decrease to about 34 ng/mi to over 74 ng/ml in the winter (6 ng/mlless than the average, half the winter to summer variation of 12 ng/ml)are well above the levels to reduce the risk of rickets, myocardialinfarction and colon cancer in the winter. A concurrent decrease indietary vitamin D, increase in winter skin exposure and decrease insummer exposure to maintain the 25-OHD levels above 27 ng/ml may retainthe current advantages for rickets, myocardial infarction and coloncancer and in addition provide the many potential health improvementsassociated with reduced dietary vitamin D excesses.

Considering the upper limit for 25-OHD, Garland, 30, recommends an upperlimit of 41 ng/ml and Jacobus, 40, recommends an upper limit of 80ng/ml. Garland as previously discussed recommends a range of 27 ng/ml to41 ng/ml for maintaining a low risk of colon cancer. The normal range of25-OHD listed by Jacobus, 40, is 22 to 200 nmol/liter (8.8 ng/ml to 80ng/ml). The upper limit for the normal range is thus 80 ng/ml.Hypervitamintosis D was associated with drinking milk with excessivevitamin D for eight patients by Jacobus, 40. The average 25-OHD levelsfor each of the eight patients ranged from 83 ng/ml to 665 ng/ml. Therange recommended by Garland provides a safety factor of about two belowthe hypervitamintosis D lower limit. The measurement of 25-OHD providesa convenient means to experimentally verify the satisfactory functioningof exposure lamps and outdoor exposure habits in maintaining recommendedvitamin D levels.

Since part of the effectiveness of vitamin D is in controlling theimportant calcium balances, sufficient dietary calcium is necessary.This is not a common problem in the U.S. However in some countries, andfor some with unique dietary habits such as strict vegetarian, thecalcium intake can be important as discussed by Prentice, 66. Lowvitamin D intake along with low ultraviolet B skin exposure results inloss of calcium. Davies, 21, found large negative calcium balances (netloss of calcium) with the fecal output of calcium nearly doubling by61-70 days after start of a confined environment experiment of nineyoung male volunteers with the low dietary vitamin D intakecharacteristic of the British diet and without ultraviolet B skinexposure.

The August exposures for office workers in Bristol, 8 mJ/sq. cm. per daymeasured by Leach, 46, and the August 25-OHD levels for Britishsubjects, Stamp, 74, about 20 ng/ml, can be used to estimate requiredlamp exposures. In Britain the average vitamin D intake is about 150IU/day. Relative to the adverse effects of vitamin D this intake has anadvantage over the much higher average intake levels in the U.S. Toachieve the 25-OHD level of 27 to 41 ng/ml recommended by Garland, 30,the estimated exposure range for a clothed individual using the 8 mJ/sq.cm. and 20 ng/ml is: 11 to 16 mJ/sq. cm. per day. If the effectivenessof whole body exposure to a clothed person exposure is ten to one thenthe estimated lamp exposure for whole body exposure is 1.1 to 1.6 mJ/sq.cm. per day. For a person with an MED of 30 mJ/sq. cm. the range is0.036 to 0.053 MED's.

The average ambient radiation for Bristol England is roughly 900 mJ/sq.cm. per week according to the measurements of Leach, 46. For Washington,D.C. the ambient solar UV (299 nm) is listed as 1,890 kJ/sq. m. per yearby Lytle, 53. The corresponding average daily values of 129 mJ/sq. cm.for Bristol and 518 mJ/sq. cm. for Washington, D.C. differ by a factorof four. Increased cloudiness and the higher latitude of Bristol resultsin an expected lower average ambient ultraviolet erythemally effectiveradiation for Bristol. The use of lamp exposure in the dark season isthus more important in the more cloudy higher latitude areas.

If the exposure is kept below 0.053 MED's per day and the lamp is usedfor the dark half of the year, then the yearly dose is less than 10MED's. Since the estimated lifetime average dose for mid-latitude areasin the U.S. such as Washington, D.C. is 85 kJ/sq. m. per year, Lytle,53, the average daily dose is about 23 mJ/sq. cm. An increase in dose of1.6 mJ/sq. cm. is a 7% increase relative to a daily average of 23 mJ/sq.cm. Since lamp exposure is needed for only about half the year, theyearly dose is increased by 3.5%.

To avoid an accumulated yearly increase in dose, the summer exposuremust be correspondingly reduced. Since the summer exposure is at such avery high rate with time for bright clear days only a small reduction inbright day exposure can compensate for the increased winter exposure. Anexposure period of 140 seconds (2.3 minutes) of clear midday outdoorJuly erythemally effective ultraviolet radiation (0.02 mW/sq. cm.) isequivalent to a typical indoor workday eight hour fluorescent lightingexposure of 2.8 mJ/sq. cm.

Lamp and window characteristics other than exposure values

In addition to selecting the lamp and outdoor exposure to obtain arecommended 25-OHD level other details of lamp selection are important.

For eye protection during indoor exposure it is desired a lamp bemounted high with low reflecting surfaces to keep the retinal irradiancein the UV blue region low. To irradiate a large fraction of the body itis desired the lamp be placed at an angle rather than directly overhead.To avoid eye irradiation and irradiate a large fraction of the body thelamp might be placed upward toward the ceiling relative to the standingposition in a shower or in front of a mirror.

In bedrooms and hospital rooms, indirect visible lighting with a shadedlamp on the wall irradiating the wall and ceiling over the top of thehead of a reclining person is desirable for eye comfort. Since mostmaterials have a low UV-B reflectivity the UV-B irradiation for areclining person can be directed toward the person from an over-the-headwall location.

There are advantages to have vitamin D generation by light exposurerather than obtaining vitamin D from the diet or supplements. In areasnot too far from the equator where sufficient sunlight is available yearround a bathroom window, other room window, door or skylight withadjustable UV transmission offers a potential lower cost than a lamprequiring electrical power use.

A UV transmitting skylight can provide a higher room irradiance forindoor sunbathing in cool weather than a window with perpendicularfarther in angle from the sun direction when the sun is high in the sky(the time of greatest UV transmission through the atmosphere). The useof a skylight in a bathroom enables whole body irradiation during theperiods when clothes do not usually cover most of the skin.

Cholesterol

Kime, 42, describes how plaque in arteries is reduced by sun exposure ofthe skin. First, the cholesterol in the skin is reduced by lightexposure converting the cholesterol to vitamin D and other compounds.When the cholesterol in the skin is maintained low for a long periodusing the light exposure the plaque in the arteries begins to decrease.High blood pressure associated with the plaque decreases as the plaqueis removed.

To obtain reduced plaque in the arteries and the potential heart diseaserisk reduction associated with plaque reduction it may be necessary toavoid excessive dietary cholesterol. As pointed out by Kummerow, 45,some areas such as rural Romania have much higher dietary cholesterolintake than the U.S. yet the rate of myocardial infarction is much lowerthan in the United States. The increased sun exposure in rural areas maybe effective in maintaining a low level of cholesterol in the skin and acorresponding low level of plaque in the arteries.

In experiments with rabbits, Altschul, 10, demonstrated serumcholesterol and arteriosclerosis could be reduced by ultravioletirradiation of the skin.

To reduce coronary heart disease mortality, cholesterol reduction bydiet modifications and drugs have been successfully used as discussedby, Gould, 34. Since total mortality is not reduced in the same manneras coronary heart disease mortality there is the question of whether ornot lower cholesterol is associated with higher mortality for conditionsother than coronary heart disease. Golier, 33, analyzed multiple studiesand found for men, increased suicide is associated with lower levels ofcholesterol.

Moderate sun exposure to reduce cholesterol in place of diet and drugtechniques may not have the disadvantage of possible increased mortalityfrom suicide since moderate light exposure is often relaxing and is usedto reduce or eliminate depression.

Reduction in exposure in bright seasons

In many areas overexposure in bright seasons is a growing problem asindicated by the increasing mortality from melanoma of the skin. Chronicexposure of untanned skin and many sunburns are risk factors formelanoma of the skin. Summer exposure on weekends while being inside therest of the week and vacations to brighter areas can be associated withincreased risk of melanoma of the skin.

For a person with sensitive skin the number of MED's in a three hourexposure in midday is as high as 15 at the equator and 10 at 40 degreeslatitude, WHO, 85, table 3.3. By staying out of the direct sunlight whenthe shadow is shorter than the person is tall the protection factor is2.7 or greater, Holloway, 39. The shadow rule for solar UV-B protectionis: sunburn is more likely when shadows are shorter than objects arehigh. This is a convenient method for reducing the possibility ofoverexposure and sunburn especially of children in the early summer.Avoidance of long term exposure to direct sunlight when the shadow isshorter than the child can be a convenient method rather than selectingclock times. The clock times for high exposure vary with standard ordaylight saving time and latitude. For darker seasons when insufficientsunlight is a common problem the midday exposure when the shadows arethe shortest are preferred. At high latitudes in darker seasons even theshortest shadow in midday is longer than the person is tall.

Balancing the exposure throughout the week and year

For indoor workers, a reduction in the weekend and vacation overexposureby clothing style and avoiding the midday bright direct sunlight canhelp balance the exposure, reduce the exposure and reduce the risk ofskin cancer.

Another approach to balancing the exposure for indoor workers is toincrease the exposure during the week. Increased exposure by very shortwalks at lunchtime or lamp exposure may help to balance the weekday andweekend exposure. This increases the exposure and risk of non-melanomaskin cancer but for many the disadvantages may be outweighed by theadvantages as discussed by Ainsley, 9. The risk of nonmelanoma skincancer is increased, however, the reduced risk of other higher mortalityconditions can reduce the overall mortality as observed for outdoorworkers such as sailors.

For office workers who have a problem with too much sunlight exposure onweekends in the summer bare tube fluorescent exposure at work during theweek provides an improved balance in exposure throughout the week. Thisincreased exposure, but with a better balance throughout the week, mayreduce the risk of melanoma of the skin. For persons who obtainexcessive sunlight every day in the bright season, bare tube fluorescentlighting in the evening is clearly a disadvantage. For those personsblocking diffusers are appropriate during the bright season.

The lower mortality for outdoor workers indicates significant lightexposure and exercise is conducive to good health for many persons.

Melanoma of the skin appears to be associated with irregular sunexposure habits and overexposure. Many sunburns are common for those whodevelop melanoma of the skin. In childhood too much midday summer sunwith sunburns, moles and freckles can indicate an increased risk inlater life. For adults and students being indoors at work or school withlots of sun exposure on weekends or vacations can increase the risk. Theproblem is irregular exposure. The skin is bleached and sensitive whenexposed to too much sunlight.

Near the equator the melanoma of the skin incidence generally is not ashigh as at the bright desert environments near 30 degrees latitude. Atthe equator the sun is nearly vertically above at the equinoxes twice ayear. In comparison at higher latitudes the sun is at a high elevationonly once a year in the summer. Consequently at the equator the sunlightis bright all year with only a small percentage variation. The averageirradiance during a month is high but it changes by only a small amountsuch as 0.22 to 0.32 watts/sq. cm., Frederick, 28. In the U.S. theirradiance varies from a high of about 0.2 watts/sq. cm. in June andJuly to very low values in the winter. Although the equatorialirradiance is higher the irradiance percentage change throughout theyear is much smaller than in the U.S. and the countries with greatlyincreasing and high melanoma of the skin incidences.

The lower incidences of melanoma of the skin near the equator indicatethe potential advantages of a balanced exposure. Usually therecommendation is to avoid sun exposure. However, to balance theexposure the exposure could be increased during the week such as a walkat lunch time and decreased on the weekend such as by avoiding middaynon-shaded direct sun exposure. The objective is to obtain the benefitsof sun exposure and avoid overexposure in a manner best suited for eachindividual with particular skin type and any special health conditions.

To balance the exposure throughtout the year the exposure can beincreased in the spring and fall by opening the car windows and rollingup the sleeves and other techniques. In the higher latitudes in thewinter the solar irradiance is so low lamps are about the only way toobtain significant exposure. For daily moderate exposure lamps at homeor work can be used to maintain sufficient skin exposure.

Tanning booths have the disadvantage they are usually used for highintensity irregular exposures to provide an excessively dark stressfultan with associated skin damage. Frequent moderate exposures with lightor no tanning is much less stressful for the skin. Since outdoor workersgenerally have a lower mortality than indoor workers exercise and lightexposure with moderate tanning may be of benefit to many persons.

Avoidance of overexposure by high sensitivity individuals

The exposures such as 0.02 MED for whole body vitamin D generation arevery low compared to casual summer exposure. Even though the exposure islow, precautions as used with ultraviolet therapy may be advisable sincesome persons may be very sensitive to the ultraviolet radiation. Forsome individuals with increased sensitivity to UV-B radiation theavoidance of excess ultraviolet exposure may be essential. Xerodermapigmentosum, sarcoidosis, Bell, 15, and other conditions require specialcare in controlling any UV-B exposure.

As discussed by Scott, 69: "There are certain skin conditions in whichthe application of ultraviolet radiation may lead to an exacerbation.These include the acute onset of psoriasis, acute eczema, lupuserythematosus, herpes simplex, and xeroderma pigmemtosum. There are alsosome general conditions in which irradiation should be used withcaution. Among these are pulmonary tuberculosis, cardiac or renalfailure, hyperthyroidism, and diabetes. Nervous, cachetic patients donot tolerate irradiation well. The administration of sulphonamidepreparations sometimes leads to prolonged and persistent sensitivity."

"Extensive treatments at home by the patient is to be avoided withoutthe supervision of a physician. Home lamps should be fitted with anautomatic switch to prevent overdosage in case the patient shouldinadvertently fall asleep. Kovacs, has shown that there are manyelectrical and mechanical dangers in carrying out home treatments."

Scott, 69, also points out whoever may face the source should wear eyeprotection and the genitalia are usually covered during irradiation.(Beneficial effects of genitalia exposure during sunbathing such ashormone production and softening the skin for childbirth are discussedby Kime, 42.) A three week progressive increase in exposure startingwith a short exposure of the feet working up to a whole body exposure isdescribed on page 257 of the article by Scott The many chemicals anddrugs that can photosensitize the skin and eyes make it desirable togradually increase any new exposure.

The appearance of skin disorders, itching or other unusual conditionsindicate the exposure should not be continued and a physician consulted.Photosensitization materials include drugs (quinine, trypaflavin, eosin,methylene blue, and other fluorescent dyes), endrocrines (insulin,adrenalin, pituitrin, thyroid) and heavy metals (mercury, iron, bismuth,gold, silver and calcium and their salts), Kovacs, 44.

Hawk, 37, describes idiopathic abnormal responses to ultravioletradiation including the most common photodermatosis, polymorphic (orpolymorphous) light eruption (PLE). PLE is more common in females thanmales and usually caused by sunlight and not by high doses of artificiallight. The skin eruption usually begins in the spring. Hawk lists twentyone diseases exacerbated by excess ultraviolet radiation: acne, actinicfoliculitis, atropic eczema, carcinoid syndrome, cutaneous T-celllymphoma, dermatomyositis, disseminated superficial actinicporokeratosis (DSAP), erythema multiforme, familial benign chronicpemphigus (Hailey-Hailey disease), keratosis follicularis (Darier'sdisease), lichen planus, lupus erythematosus (LE), pellagra, pemphigusfoliaceus (erythematosus), pityriasis rubra pilaris, psoriasis,reticulate erythematous mucinosis (REM) syndrome, rosacea, seborrheiceczema, transient acantholytic dermatosis (Grover's disease), and viralinfection. For persons with these disorders, physician consultation andthe avoidance of excess ultraviolet exposure is of increased importance.

Harber, 35, describes abnormal responses to ultraviolet radiationresulting from drugs and chemicals. Phototoxic chemicals include dyes,coal tar derivatives and furocoumarins. Photoxic drugs include:amiodarone, benoxaprofen, demethylchlortetracycline, doxycycline,furosemide, nalidixic acid, naproxen, phenothiazines, piroxicam andsulfonamides. He also lists major photoallergenic drugs and chemicalsincluding particular halogenated salicylanilides, antifungal drugs,phenothiazines, suncreens, whiteners, fragrances and sulfanilamides.Photoxic reactions normally occur within 24 hours. Photoallergenicreactions may not appear for periods such as 10 days later. For personswith these types of photosensitive reactions physician consultation andavoidance of excess ultraviolet exposure is of importance.

Light skin persons living in bright climates have high sensitivity tosunlight relative to those with darker skin better adapted for the localclimate. In the U.S. light skin persons living in southern brightclimates typically have problems with summer overexposure. Dark skinpersons living in the northern darker climate typically have greaterproblems with winter underexposure. The average 25-OHD blood level inPalm Beach is approximately 80 ng/ml, Neer, 58, and even higher valuesare expected in the summer and for outdoor workers.

Those living in bright climates in high elevation areas are exposed tovery high levels of UV-B. The shorter path through the atmosphereresults in less atmospheric absorption and scattering of the UV-B solarradiation. The avoidance of bright season overexposure in the highelevation areas thus can be important, especially for light skinpersons. The benefit of the relatively high exposure in other seasonsmay offset the disadvantage of the high summer exposure. Scragg in hischapter 9 in the 1995 CRC book Calcium-Regulating Hormones andCardiovascular Function edited by M. Crass III and L. V. Avioli pointsout that both coronary heart disease (CHD) mortality and elevation varywith longitude in the United States (but in opposite directions). Highelevation areas in the west have much lower CHD mortalities than lowerareas in the east. Scragg concluded the increased ultraviolet radiationat higher elevations is the most likely factor explaining thelongitudinal variation of CHD mortality.

The malignancy mortality also varies in a manner similar to thevariation of CHD with longitude. Increased ultraviolet radiationespecially in the dark seasons thus may reduce the mortality frommalignancies. Multiple sclerosis varies relatively uniformly withlatitude across the United States. The longitudinal variation in theUnited States characteristic of CHD and malignancy mortalities is notapparent for MS. Visible light, temperature or some other factor mayinfluence the risk of multiple sclerosis. UV-B (if it is a risk factor)is not likely to be as strong a risk factor for multiple sclerosis asother factors.

Vieth, 79, discusses a possible mechanism for vitamin D toxicity. Highlevels of plasma 25-OHD may displace 1,25 dihydroxyvitaminD from theplasma. Excess vitamin D symptoms are similar to vitamin D deficiencysymptoms as discussed in the U.S. Department of Health and humanServices publication 88-2117 on Some Facts and Myths of Vitamins. Insouthern states solar radiation stimulated levels of 25-OHD are high formany individuals. For persons with very high levels of 25-OHD due todietary intake of vitamin D and sun exposure the use of additional lampinduced vitamin D thus may be detrimental and should be avoided.

By using low irradiance lamps for low daily whole body exposures innorthern areas in the dark seasons and avoiding excess exposure inbright seasons the risks of home use are greatly reduced. The exposuresfor whole body stimulation of vitamin D formation in the skin are ingeneral much lower than the exposures used for treatment of skindisorders. By observing the precautions developed for skin disordertreatment such as using timers in case the person being exposed fallsasleep, the safety of exposure is increased. Physician consultation isneeded for selecting exposure conditions for those persons who haveabnormal photosensitive reactions.

Summary

For good health, exposure to a variety of wavelengths is needed. Abalance in the exposure from day to day and throughout the year isnecessary. Avoidance of overexposure by having moderation in theexposure is essential to prevent skin cancer and other disorders. Excessvitamin D in the diet should be avoided. The diet should be balancedincluding sufficient fruits, vegetables and antioxidants. A brightenvironment is desirable for a feeling of well being and avoidingpsychological depression.

The present invention can enhance the probability for good health andreduce the risk of diseases associated with solar radiation exposure anddiet for those persons with deficient, excess or non-balanced exposureand diet. A key feature of the invention is the use of whole bodyexposure when possible. This enables the use of very low irradiances forshort periods. A slight reduction in the bright season exposure can thenmore than offset the increased dark season exposure. This results in anoverall reduction in the risk of skin cancer. Several techniques areincluded to increase the UV-B exposure in cold dark seasons when adeficiency in UV-B exposure is common.

V BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with accompanying drawing forming a part of thisspecification and in which similar numerals of reference indicatecorresponding parts in all the figures of the drawing.

FIG. 1 is a graph of the average daily sunlight exposure over the courseof a year.

FIG. 2 is a graph of the U.S. mortality rate for the year 1990.

FIG. 3a and FIG. 3b are graphs of the U.S. Breast and Colon cancermortality rates for 1989 and 1990.

FIG. 4 is a graph of the Alaska mortality rate for 1989 and 1990.

FIG. 5 is a graph of various countries' mortality rates over 5 yearperiods from 1955 through 1989.

FIG. 6 is an oblique view of an embodiment of the window assembly of thepresent invention.

FIG. 7 is an enlarged horizontal sectional view taken along line 7--7 ofFIG. 6.

FIG. 8 is a schematic view of an embodiment of the vehicle sun roof ofthis invention.

FIG. 9 is a schematic view of an embodiment of a garment withtransmitting windows.

FIG. 10 is an enlarged horizontal sectional view taken along line 10--10of FIG. 9.

FIG. 11 is a schematic back view of an embodiment of a protectivegarment.

FIG. 12 is a schematic back view of the protective garment of FIG. 11with the hood stowed in the hood pocket.

FIG. 13 is a schematic view of an embodiment of a lamp fixture withadjustable ultraviolet output.

FIG. 14 is a sectional view taken along line 14--14 of FIG. 13.

FIG. 15 is a schematic view of the FIG. 13 lamp fixture adjusted forminimum ultraviolet radiation output.

FIG. 16 is a schematic view of an embodiment of a skylight withadjustable ultraviolet radiation transmission controlled by a motordrive.

FIG. 17 is a sectional view taken along line 17--17 of FIG. 16.

FIG. 18 is a schematic perspective view of a combined fluorescent andincandescent lamp fixture.

FIG. 19 is a schematic view of fluorescent light fixtures for a shower.

FIG. 20 is a perspective view of a fluorescent lamp fixture for ahospital bed.

FIG. 21 is a schematic view of a wall mount quartz halogen lamp fixture.

FIG. 22 is a schematic view of the FIG. 21 wall mount fixture over abed.

FIG. 23 is a schematic view of a lighting device for exposure of anindividual during exercise periods.

VI DESCRIPTION OF THE PREFERRED EMBODIMENTS

The above and other objects and advantages and novel features of thepresent invention will become apparent from the following detaileddescription of the preferred embodiment of the invention illustrated inthe accompanied drawings, wherein:

Adjustable ultraviolet transmission window

FIG. 6 is an adjustable window, 11, of know construction which iscurrently available. The sections are positioned for intermediateultraviolet transmission;

Referring now to the sectional view in FIG. 7, the outer frame, 12,along with the side supports, 13, are used to support the movablewindows 19, 22, and 18. The ultraviolet transmitting window is the outerwindow, 19. The windows in the middle, 22, and inner, 18, units blockthe ultraviolet UV-B (280-315 nm) radiation.

A window insert, 24, is held by a grommet, 27. The window is guidedalong the track by the guide, 26. The retractable pins, 34, enable thewindow to be positioned manually using the handles, 31. The pins areheld engaged in positioning holes, 43, by the springs, 45, located inholders 40.

Referring now to FIG. 6, for maximum ultraviolet transmission, the innerwindow, 18, is lowered so the outer ultraviolet transmitting window, 19,is unobscured. For maximum blocking of the ultraviolet radiation theinner window, 18, is raised to the top to block the ultravioletradiation passing through the outer window, 19. For intermediateultraviolet transmission, the inner window, 18, is positioned at anintermediate position as illustrated in FIG. 6.

The UV transmitting window, 19, has an insert, 44, composed of materialthat is substantially transparent to light rays from the ultraviolet,visible, and part of the infrared solar spectrum. The UV blockingsections, 18, and 22, are substantially transparent to the visible andinfrared solar radiation. The side frames, 13, hold the windows andallows them to be positioned for high, intermediate or very lowultraviolet radiation transmission.

To raise or lower a window the two positioning pin handles, 31, aremoved toward each other by actuator means to release the pins from thepositioning holes freeing the window. The window is then moved up ordown by actuators and the pins are released when the window is in thedesired position. When the pins engage the holes the window is held inplace and the actuators can be released.

The material of which the ultraviolet transmitting window, 19, insert,44, is composed is an optically transmitting material such asultraviolet transmitting glass or plastic similar to the materialsdescribed by Driscoll, 23, and by Sliney, 73, hereby incorporated intothe present application by this reference. Briefly the materials areglasses such as Pyrex, trademark, that transmit a fraction of theultraviolet B radiation and are not extremely high in cost. Otherglasses such as Vycor, trademark and fused silica transmit a higherfraction of the ultraviolet radiation but the cost is prohibitive formany applications. Plastic materials such as Corex-D, trademark, andPlexiglas, trademark, have high transmission in the UV-B. However, manyof the plastic materials are not solar resistant and darken upon longterm exposure to sunlight and are satisfactory only for low exposure.

The material of which the ultraviolet B radiation blocking inserts, 23and 24, are composed is conventional window glass or plastic.

The general UV-B non-direct solar radiation environment in a room isincreased when the UV-B transmitting area is increased. In any area withdirect solar irradiation through a specularly transparent window thearea irradiated by UV-B is increased when the UV-B transmitting area isincreased. The direct irradiation is not altered. The risk ofoverexposure is reduced by use of a diffusely UV-B transmitting window19, insert, 44, of the preferred embodiment

A meter can be used to measure the ultraviolet solar radiationtransmitted by the window. Estimates of the appropriate exposure for aperson with particular skin type is needed to determine the exposuretime for window transmitted or lamp generated ultraviolet B radiation.

Adjustable ultraviolet transmission sunroof

FIG. 8 is an adjustable ultraviolet transmission sunroof, 65, for avehicle, 60. The outer element, 62, is ultraviolet diffuselytransmitting material. The inner sliding element, 64, blocks theultraviolet radiation and attenuates the visible light. By positioningthe inner sliding element, 64, the ultraviolet transmission can beadjusted. The method of operation is similar to the window in FIG. 1.The inner section, 64, is partially transparent to visible light toavoid glaringly bright light transmission when the sun is overhead.

A person receiving too little or too much ultraviolet B radiation canadjust the sunroof, 65, for appropriate UV-B transmission. A personreceiving sufficient UV-B radiation while outside the vehicle canposition the sliding element, 64, to block the ultraviolet B radiation.

Ultraviolet radiation transmitting garment

FIG. 9 is a garment, 70, with a first body portion, 74, with a secondportion 71 including sleeves 72, with the second portion including athird portion 76, including windows 77. The windows, 77, are composed ofmaterial that is substantially transparent to light rays from theultraviolet, visible, and infrared solar spectrum and in particular UV-Bradiation. The material of which the windows, 77, are composed is anoptically transmitting material such as plastic, safety glass or wovenfabric of plastic or glass fibers. The window, 77, can be attached tothe garment, 70, using thread, 75, and stitching holes, 73, in the edgesof the window. For some materials such as thin flexible plastic thestitching holes, 73, are not necessary as the window can be machine sewnto the garment, 70. A long sleeve shirt, 78, can be worn under the coatto avoid overexposure during midday in bright cold environments such asin high altitude areas. The sleeves can be rolled down in midday forprotection. In the morning and late afternoon the sleeves can be rolledup to provide UV-B exposure of the skin as needed.

FIG. 10 is a sectional view of the garment, 70, taken along line 10--10of FIG. 9. The windows, 77, in the sleeves, 72, are attached by stitches75, to the inner fabric layer 79, and the outer fabric layer 71.

Garment for protecting the skin from excessive solar radiation exposure

FIG. 11 is a garment, 80, for protecting the skin from overexposureincluding body portion, 81, and arms, 85, 87. A hood 82, can be used toshade the head and neck. A novel feature is the pocket 83, for stowingthe hood when it is not in use. FIG. 12 shows the garment, 80, with thehood, 82, stowed in the pocket 83.

The loose fitting garment body portion, 81, allows ventilation forcooling by removal of humid air near the skin during hot weather. Thematerial of which the garment, 80, is composed is a fabric, 84, such aswhite woven cotton strands. This material provides transmission of avery small fraction of the solar radiation suitable for exposure of theskin. The white color provides reflection of a large fraction of thesolar radiation for maintaining coolness in a hot environment. Thismaterial for a loose fitting garment permits ventilation and allowsmoisture transmission and or absorption for cooling of the wearer byevaporation of moisture from the skin.

Referring now to FIG. 11, when a person is wearing the garment, 80,indoors or elsewhere where the hood, 82, to shade the head from sunlightis not needed, the hood 82, can be stowed in the pocket 83, as shown inFIG. 12.

Adjustable ultraviolet radiation output light fixture

FIG. 13 is a light fixture, 90, having side walls, 91, and end walls,94, for providing adjustable UV-B radiation and light in an indoorenvironment. It is particularly well suited for use in a bathroom toprovide whole body exposure during bathing. The UV-B radiation isemitted from fluorescent lamps, 95. Stationary UV-B blocking diffusers,96, are located at the ends of the fixture, 94. UV-B blocking movablediffusers 97 can be used to adjust the amount of UV-B radiation emittedby the unit.

FIG. 14 is a sectional view of the light fixture, 90, along line 14--14of FIG. 13. Referring now to FIG. 14 the two fluorescent lamps, 95, emitthe visible, infrared and ultraviolet radiation. The portion of theradiation striking the diffusers, 96 and 97, is partially diffused andpartially absorbed. The material for the diffusers, 96 and 97, isselected so that most of the visible radiation is diffused and most ofthe UV-B radiation is absorbed. This is a characteristic of mostcurrently used diffuser materials.

FIG. 15 is an oblique view of the light fixture, 90, with the movablediffuser sections 97, positioned to block the UV-B radiation.Positioning of the movable diffusers 97, between the full open positionshown in FIG. 13 and the full closed position shown in FIG. 15 providesintermediate levels of the UV-B radiation environment.

By mounting the fixture 94, facing upward on a wall, rather than on aceiling facing downward, a more uniform indirect irradiation can beprovided. In addition to providing a more uniform UV-B radiationenvironment, the visible light environment is more comfortable for theeyes without bright ceiling sources of light. This is especiallyimportant for a reclining person in some situations such as in ahospital bed. A UV-B meter, not shown, can be used to adjust the movablediffusers, 97, to provide the desired UV-B environment. For indirectUV-B lighting special ceiling materials are necessary. Most materialsother than metals have very low UV-B reflectance.

Skylight with adjustable ultraviolet radiation transmission

FIG. 16 is a skylight, 100, having body portion, 109, and lead screw,102, for positioning of the UV-B blocking element, 101. A stationaryUV-B blocking element, 104, is located at one end of the skylight.

FIG. 17 is a sectional view along line 17--17 in FIG. 16. A rider, 105,on the lead screw, 102, is attached to the movable UV-B blockingelement, 101. The stationary blocking element, 104, is located near andparallel to the movable element, 101, as shown in FIG. 16. The drivemotor, 103, can be remotely controlled to position the movable elementto increase or decrease the area transmitting UV-B radiation. The outerelement, 108, diffusely transmits ultraviolet, visible and part of theinfrared solar radiation. The outer element also serves as a weathershield for rain, snow, sleet and wind.

Combined fluorescent and incandescent light fixture

FIG. 18 shows an embodiment of the combined fluorescent and incandescentlamp fixture. The fixture is primarily for use in a bath room over amirror, however, it can be used over a kitchen sink or other location.The fluorescent lamp can be used in the dark winter months to obtainultraviolet skin exposure for formation of vitamin D. In the othermonths when sufficient or excess skin exposure is obtained from casualsun exposure the incandescent lamps can be used. The use of theincandescent lamps with very low ultraviolet radiation output duringperiods of sufficient sun exposure reduces the risk of skin cancer andother diseases associated with ultraviolet radiation overexposure.

The fixture, 120, includes a fixture mounting box, 121, to which isattached a reflective plate, 122. A fluorescent lamp holder epends fromand is integral with box, 121. A fluorescent lamp, 124, extendslongitudinally below box, 121. Incandescent lamps, 125, are mounted onbox, 121, and are located behind a diffuser, 126. An incandescent lampswitch, 127, controls the incandescent lamps, 125, and a fluorescentlamp switch, 128, controls the fluorescent lamp, 124.

The switches 127 and 128 on the side of the fixture can be used toselect either the fluorescent lamp, the incandescent lamps, or bothtypes of lamps. A convenient wall switch, not shown, can then be used toroutinely turn the selected lamp (or lamps) on or off.

This fixture has the advantage of ease of retrofit in many existingbathrooms. Many baths have a fixture over a mirror. The wiring for anold fixture normally can be used for a new fixture. The existing switchor switch holder with new switch can-be used for the new fixture. Thiseliminates the need for expensive wall and wiring modifications.

Another advantage of the fluorescent lamp fixture in the bathroom is theopportunity for exposing large areas of skin while in front of themirror and while bathing. With large area skin exposure the vitamin Dcan be formed with an exposure that is a much smaller fraction of anMED. Also the cholesterol over a larger area of the skin is converted tovitamin D and other compounds. In the work environment normally only thehead, neck, arms and hands are exposed to the light environment. Onlysome workplaces have bare tube fluorescent lighting with significantUV-B for vitamin D formation needed in the winter. These workplaces havethe disadvantage of providing additional UV-B for those who obtain toomuch daily solar radiation exposure in the summer. For those withincreased weekend exposure, bare tube fluorescent lamp irradiationduring the week can improve the day-to-day balance between weekday andweekend exposure.

Ultraviolet B lamp fixture for use over a shower or bathtub

FIG. 19 is a schematic view of a fluorescent lamp fixture, 140, forwhole body exposure during bathing. Multiple lamps, 144, are utilizedfor uniformity of irradiation and sufficient ultraviolet B exposureduring the period while in the shower or a tub. A switch, 141, is usedto turn the lamps on and a timer, 143, is used to automatically turn thelamps off to avoid overexposure. The lamps are supported in the frame,142. The frame, 142, is mounted on the walls or ceiling. The lamps, 144,have protective covers, 146, to prevent breakage if bumped and to sealout moisture.

Ultraviolet B lamp mixture for use over a hospital bed

FIG. 20 is a perspective view of a fluorescent lamp fixture, 160, for ahospital bed. The lower flap section, 163, plate 162 can be opened tothe position shown for exposure of a patient to the ultraviolet Bradiation from the fluorescent lamp, 168. The bed lamp switch, 161, isused to turn the lower bed lamp on. The timer, 165, is used to turn thebed irradiation lamp off to avoid overexposure. The room light switch,175, turns the upper room illumination lamp, 173, on or off. When theupper diffuser, 164, is rotated up the room irradiation containsultraviolet B irradiation. When the upper diffuser, 164, is rotated downto cover the upper lamp, 173, the diffuser blocks ultraviolet Bradiation. The upper diffuser, 164, transparent to visible light,transmits light for general indirect room lighting when rotated downover the fluorescent lamp.

For patient body exposure to ultraviolet B radiation the lower diffuser,163, is rotated down to allow passage of the ultraviolet B radiationthough the opening as shown in FIG. 20. Following the irradiation periodwhen further ultraviolet B radiation is not needed the lower diffuser,163, can be rotated up to block the ultraviolet B radiation from thelower lamp, 168, but still transmit visible light for reading andgeneral illumination. The diffuser, 162, provides additional visuallight diffuse transmission for reading and illumination.

The opaque baffle, 167, enables the bed and room illumination to becontrolled separately using tile switches, 161 and 175.

Quartz halogen lamp wall mount fixture

The wall mount fixture, 180, shown in FIG. 21 using a quartz halogenlamp, 182, is smaller than the fluorescent lamp fixture, 160, of FIG. 20for convenience for home use over a bed or other area.

The lamp can be turned on using the switch, 181. A timer, 183, is usedto turn the unit off to reduce the risk of overexposure. A shield, 184,is used to shade the small bright source to reduce the possibility ofeye damage and for general visual comfort. The reflector, 186, directsthe light toward the exposure area.

The components of the wall mount fixture, 180, include the reflector,186, the quartz halogen lamp, 182, the lamp holders, 185, and the lampshield, 184. Electrical wires for the lamp and switch are not shown. Forhigher irradiances or modified spectrum the quartz halogen lamp can bereplaced by a mercury or other type lamp.

The use of a bed, FIG. 22, during skin exposure enables a person to useboth the supine and prone positions to expose both the front and back.Most chairs enable front exposure but are not suitable for exposure ofmuch of the back area.

Device for exposure during exercise

FIG. 23 is a lighting device for exposure during exercise. The greaterblood flow during exercise enables more of the body blood pool tocirculate to areas near the skin surface for exposure during theexercise period. This provides winter indoor exercise conditions closerto the outdoor summer exercise environment. The device, 190, includes:light bar, 195, light bar supports, 192, and lights, 194. The lights,194, provide a small amount of ultraviolet B irradiation selectedaccording to an individuals skin type. A timer, not shown, is used tocontrol the exposure period to prevent overexposure.

The light arrangement provides irradiation of legs and arms in additionto the back. The use of lights attached to the exerciser enablesexposure control with repeatable exposures on different days incomparison with non-attached lights without effective control of thelamp to subject distance. The use of shorts and short sleeve garmentsduring exercise allows exposure large areas of skin. This enablesvitamin D generation at low exposure doses. The exposure can reduce thecholesterol in the irradiated skin. Repeated use of the lamp or sunexposure over long periods of time potentially can reduce plaque in theblood vessels and arteries and reduce high blood pressure, Kime, 42.

Along with the light exposure it may be necessary to avoid dietaryexcesses of cholesterol. This may be necessary to limit the amount ofcompounds other than vitamin D formed after the maximum amount ofvitamin D is generated. To reduce the amount of the light-generatedfree-radical alpha cholesterol, sufficient dietary antioxidants areimportant, Kime 42.

What is claimed is:
 1. A garment for controlling the transmission of ultraviolet light comprising:a first body portion to surround at least a portion of the body of the wearer; at least one second portion extending outwardly from said first body portion; at least one third portion located within said second portion; said third portion being made of a material which is transparent to light rays from the ultraviolet, visible and infrared spectrum.
 2. A garment according to claim 1 wherein said second portion and said third portion are located in at least one arm portion of said garment.
 3. A garment according to claim 2 wherein the light transparent material is selected from polyester, polyvinyl, safety glass, and woven glass fibers.
 4. A garment according to claim 2 including a long sleeve shirt which is adopted to cover some or all of said light transparent material, to control the amount of ultraviolet exposure.
 5. A garment according to claim 4 including means for varying the extent to which the shirt covers said transmitting material.
 6. A garment according to claim 2 including means for protecting skin from exposure of radiation.
 7. A garment according to claim 2 wherein a hood made of ultraviolet blocking material protects the wearer from excessive radiation.
 8. A garment according to claim 7 including means for storing said hood when protection from excessive radiation is not needed. 